ensure-sphinx: Use python3

All our platforms are Python 3 now, so we can simplify this.  We can
remove the virtualenv dependency as ensure-pip installs venv and sets
variables for us to use it when making a virtualenv.

Change-Id: I98c3da5b02a4ac7fb9d7bd8e00170762e77b9f40

roles/ensure-sphinx/README.rst

@@ -25,9 +25,10 @@ All pip installs are done with a provided constraints file, if given.
    By default this list is empty.
 
 .. zuul:rolevar:: sphinx_python
-   :default: python2
+   :default: python3
 
-   Version of python to use, either ``python2`` or ``python3``.
+   **Deprecated**
+   Version of python to use, only supports ``python3``.
 
 .. zuul:rolevar:: zuul_work_virtualenv
    :default: ~/.venv

roles/ensure-sphinx/defaults/main.yaml

@@ -1,5 +1,6 @@
 zuul_work_dir: "{{ zuul.project.src_dir }}"
 zuul_work_virtualenv: "{{ ansible_user_dir }}/.venv"
-sphinx_python: python2
-doc_building_packages: "{{ _doc_building_packages | default([]) }}"
+sphinx_python: python3
+doc_building_packages:
+  - sphinx
 doc_building_extra_packages: []

roles/ensure-sphinx/tasks/main.yaml

@@ -2,10 +2,6 @@
   include_role:
     name: ensure-pip
 
-- name: Install virtualenv
-  include_role:
-    name: ensure-virtualenv
-
 # NOTE: gettext command is provided by gettext-base package,
 # so we need to check a command provided by gettext package.
 - name: Check for gettext installed
@@ -41,15 +37,12 @@
       done
   register: requirements_file
 
-- name: Gather python version variables
-  include_vars: "{{ sphinx_python.split('.')[0] }}.yaml"
-
 - name: Install base doc building packages
   pip:
     name: "{{ doc_building_packages | union(doc_building_extra_packages) }}"
     chdir: "{{ zuul_work_dir }}"
     virtualenv: "{{ zuul_work_virtualenv }}"
-    virtualenv_python: "{{ sphinx_python }}"
+    virtualenv_command: "{{ ensure_pip_virtualenv_command }}"
     extra_args: "{{ upper_constraints | default(omit) }}"
 
 - name: Install found doc requirements
@@ -57,6 +50,6 @@
     requirements: "{{ requirements_file.stdout }}"
     chdir: "{{ zuul_work_dir }}"
     virtualenv: "{{ zuul_work_virtualenv }}"
-    virtualenv_python: "{{ sphinx_python }}"
+    virtualenv_command: "{{ ensure_pip_virtualenv_command }}"
     extra_args: "{{ upper_constraints | default(omit) }}"
   when: requirements_file.stdout_lines

roles/ensure-sphinx/vars/python2.yaml

@@ -1,2 +0,0 @@
-_doc_building_packages:
-  - sphinx<2.0

roles/ensure-sphinx/vars/python3.yaml

@@ -1,2 +0,0 @@
-_doc_building_packages:
-  - sphinx